Printing plate solidifying and dimensioning method



July 21, 1953 D. c. COTTRELL ETAL 2,645,998

PRINTING PLATE SOLIDIFYING AND DIMENSIONING METHOD Filed Jan. 3, 1949 4Sheets-Sheet 1 LNVENTURJ J y 9 1953 D. c. COTTRELL ET AL 2, 5,99

PRINTING PLATE SOLIDIFYING AND DIMENSIONING METHOD Filed Jan. 3, 1949 4Sheets-Sheet 2 L INVENTORS W C W By M cf cm f Yoryey July 2 1953 D. c'.COTTRELL ETAL PRINTING PLATE SOLI IIDIFYING AND DIMENSIONING METHOD 4Sheets-Sheet 3 Filed Jan. 5, 1949 filler/75y KM RM mm NM \m A \w mm Q y21, 9 3 D. c. COTTRELL ETAL 2 9 PRINTING PLATE SOLIDIFYING ANDDIMENSIONING METHOD Filed Jan. 5; 1949 4 Sheets-Sheet 4 VAD m a i5 i4INVENTORS W Patented July 21, 1953 PRINTING PLATE SOLIDIFYING ANDDIMENSIONING METHOD Donald 0. Cottrell, Fox Point, and Carl 0. Sweet,Whitefish Bay, Wis., assignors to C. B. Cottrell & Sons Company,Pawcatuck, Conn., a corporation of Delaware Application January 3, 1949,Serial No. 68,762

3 Claims. 1

This invention relates to a method and apparatus for acting uponprinting plates for the purpose of more precisely dimensioning the same,for the purpose of modifying the location of the plane of the printingface, and for the purpose of reducing lack of uniformity in density ofthe plate material; and it resides more specifically in an improvedmethod and apparatus by means of which the metal alloy composing theplate is subjected to pressure induced deformation sufiicient to producecorrection or modification of the plate and at the same time toestablish a transitory condition of increased machinability due to coldworking, and then while said transitory condition of increasedmachinability is still prevailing the plate is immediately leveled bysubjecting the same to machining or shaving.

Heretofore printing plates such as electrotype plates, stereotype platesand the like have been acted upon with success for the purpose of moreprecisely positioning the plane of the printing face with respect to theback of the plate. At times this work is performed by very skillfullyhand hammering the back of the plate while in contact with a truesurface and thereafter machining or shaving the back of the plate, Thehand hammerin of the plate requires ahigh degree of skill and is atimeconsumingoperation. Apparatus for mechanically correcting the plane ofthe printing face of a plate is in wide use. Such apparatus depends uponthe use of pressing equipment which forces a plurality of small pressurepoints into the back of the plate while resting on a true surface. Aftera plate has been thus treated, to produce so-called cormotion orsolidification thereof it is subsequently placed in apparatus designedto machine or shave the back of the plate to a surface which is closelyparallel to the printing face of the plate.

When desired to introduce into a printing plate so-called treatment?that is to say to bring about the formation of selected areas in theprinting face of the plate which are at slightly different levels, forthe purpose of improving the printing effect of the plate, the plate isacted upon in a manner related to that described above, the plate beingsubjected to pressure sufficient to produce deformation while in contactwith carefully prepared masks of proper thickness. solidification,leveling or treatment whether produced by hand hammering or otherwiseare all usually followed by precise machining, or shaving of the back ofthe printin plate. This final cutting away of metal from the back of theplate has, however, heretofore been performed as a separate step someminutes or hours after the metal has been deformed.

It is the discovery of this invention that metal alloy such aselectrotype backing metal, stereotype metal or other such alloys(usually containing lead as the chief constituent) when in the form of aprinting plate and when subjected to pressure to cause deformationsufficient for the purpose of solidifying the plate or correcting ormodifying the position of the plane of the printing face, that the metalalloy so deformed, momentarily acquires a transitory condition ofincreased machinability which permits more precise machining or shavingof the plate if machining or shaving is performed while such transitorycondition is still prevailing. It is an object of this invention toprovide methods and apparatus which cause shaving or machining of theplate to take place while this transitory condition of increasedmachinability is prevailing. This and other objects and advantages ofthis invention will be more fully explained in the descriptionfollowing.

This invention is herein described by reference to the accompanyingdrawings forming a part hereof wherein there is set forth by way ofillustration and not of limitation one form of the apparatus of thisinvention suitable for carrying on illustrative instances of the methodof this invention.

In the drawings:

Fig. 1 is a side view in elevation with parts broken away and in sectionof one form of the apparatus of this invention,

Fig. 2 is an end view in elevation of the apparatus shown in Fig. 1,

Fig. 3 is an enlarged detailed side view in elevation and in section ofthe upper part of the apparatus shown in Fig. 2 the same being viewedthrough the broken plane indicated at 3-3 in Fi 6, r

Fig. Fl is an enlarged diagrammatic detailed fragmentary side View inelevation and in section of a plate undergoing solidification,flattening and shaving,

Fig. 5 is an enlarged diagrammatic detailed fragmentary side View inelevation and in section of a plate undergoing treatment to modify itsprinting face and being subjected to shaving.

Fig. 6 is an enlarged detailed end View in elevation and partly insection of the upper part of the apparatus illustrated in Fig. 1, viewedin part in section through the plane 66 there indicated,

3 showing parts which act to vertically adjust the solidifying andflattening roll,

Fig. '7 is a fragmentary detailed end view in elevation and partly insection of the treating roll elevating mechanism of the apparatus shownin Fig. l, the same being viewed in part in section through the brokenplane 'I'I there indicated,

Fig. 8 is a fragmentary detailed side view in elevation of the portionof the apparatus shown in Fig. l which is detailed in Fig. 7, and

Fig. 9 is an enlarged detailed view in developed form of a fragment ofthe surface of the solidifying roll of the apparatus shown in Fig. 1.

As shown in the drawings, particularly in Figs. 1 and 2, the form of theapparatus of this invention, there set forth for illustrative purposes,is provided with a rigid sub-base I, surmounted by a bed designatedgenerally by the numeral 2. Extending longitudinally of the bed 2 is apair of parallel ways 33 which support for horizontal longitudinalmovement a carriage designated generally i. Bed 2 is open between andbelow the ways 3-3 which opening accommodates a horizontally disposedhydraulic feed cylinder 5 in which there is mounted for longitudinalmovement a piston rod 6. The end of piston rod 6 cpposite cylinder 5 isconnected by means of a rigid arm I to the carriage 4 for impartinghorizontal movement thereto on introduction and withdrawal of hydraulicfluid into and from within the cylinder 5. Hydraulic fluid for actuationof the piston rod 6 is supplied in known manner by pump 8 driven bymotor 9. The connections between the pump 8 and the cylinder 5 are notshown, but are arranged in known manner to be controlled by controllever I6 which when shifted in one direction causes movement of thecarriage 4 toward the left and when shifted in the opposite directioncauses movement of the carriage 4 more rapidly toward the right.

Any convenient means other than an hydraulic system may be employed tobring about movement of the carriage 4.

Enclosed within the carriage 2', in an opening provided therefor, is avertically adjustable platen II having downwardly projecting inclinedlands which slidingly engage an adjustable wedge |2 which in turnthreadingly engages an adjusting screw I3. Adjusting screw I3 isrotatably mounted in the right hand end of carriage 4 and there heldagainst end Wise movement with respect to the carriage Secured to theend of screw I3 is a hand adjusting wheel I4 by means of which thehorizontal position of the wedge I2 may be adjusted. Horizontaladjustment of the wedge I2 in turn brings about vertical adjustment ofthe platen II.

The working stroke direction of movement of carriage 4 is toward theleft as viewed in Fig. l and ther is provided near the right hand end ofplaten II a vertically projecting thrust lug I5 intended to engage theedge of a flat printing plate reposing on the upper surface of theplaten II for the purpose of compelling movement of the plate with theplaten I I during the working stroke.

Mounted above the platen I I on rigid side frame members I6 and I1 is aplate processin assembly, the same being shown in greater detail in Fig.3. Included in the plate processing assembly as subassem'blies thereofare a smooth-roll, plate-treating sub-assembly designated generally bythe numeral I8, a dentated-roll, plate-solidifying subassemblydesignated generally by the numeral I9, and a plate shaving sub-assemblydesignated generally by the numeral 20.

The smooth-roll plate-treating sub-assembly I8 is intended primarily foracting upon a printing plate through the medium of so-called face orback mats to bring about alteration of the level of local areas of theprinting face of a printing plate in a manner to be more fully describedhereinafter. The principal element of sub-assembly I8 is a smooth,rigid, cylindrical roll 2| mounted at its ends for free rotation inbearings 22 and 23, one of which is shown in detail in Fig. '7. Bearings22 and 23 are carried in turn in eccentric bearing capsules 24 and 25,arranged to be angularly shifted to raise and lower the treating roll2|. Eccentric bearing capsules 24 and 25 are closely fitted for limitedangular adjustment within cylindrical seats formed in the side framemembers I6 and IT. Secured to the eccentrio bearing capsule 24 and 25respectively, are radius arm 26 and 2'I.

As appears more clearly in Fig. 8 radius arm 26 is pivotally joined atits outer end to a con necting link 28 which in turn is pivotallyconnected to radius arm 29 which forms a part of a bell crank assembly,made up of the arm 29 and a hand lever 38 both secured to a bell crankshaft 3|. The shaft 3| extends through bearing 32 in side frame I6horizontally across the machine to and through a similar bearing in sideframe member I? where it carries a crank arm 23 securely held in placethereon. Crank arm 33 is disposed in angular alignment with arm 29 andis pivotally connected with a link 35 which is pivotally joined in turnwith the end of radius arm 2'5. Rotation of the shaft 3| forming a partof the bell crank assembly by manipulation of hand lever 30 causessimultaneous rotation of eccentric bearing capsules 2 5 and 25 with anattendant raising and lowering of roll 2 I.

As appears from the drawings, the eccentricity of capsules 25 and 25 issuch that roll 2| occupies a lower position when the parts are in theposition shown in the drawings. In this position link 23 and arm 29 onthe one hand and link 3d and arm 33 on the other hand are respectivelyin alignment and thus through a toggle effect securely hold the capsules24 and 25 against rotation with little torque being applied to the bellcrank assembly. A detent pin 35 s-lideably held in a projection of arm29, engages a recess not shown, beneath the same in side frame IS thesame being adequate to maintain the roll 2| in lowered position eventhough very heavy upward forces are applied thereto. On the other hand,when it is desired to raise the roll 2| the same may be quicklyaccomplished by withdrawing the detent 35 and moving the hand lever 3|]to the broken line position indicated in Fig. 8, whereupon the detent 35may engage the recess 36 to hold the roll 2| in raised position. In thisway the roll 2| may be quickly released and raised or quickly loweredand locked in a precisely determined lowered position.

As pointed out above, the smooth roll 2| may be employed for the purposeof so-called treatment of a plate to bring about alteration in thelevels of the printing face thereof. This may be accomplished asillustrated in Fig. 5 by placing a previously flattened and preciselymachined printing plate B'I upon the platen I I having first placed incontact with the printing face of the plate a so-called face mat 38.There may also be placed in contact with the back of plate 37 a back mat39 having open portions opposite the face mat 38. The mats 38 and 39 areformed in known manner from paper or other material of predeterminedthickness and may be employed in single or multiple layers to obtain athickness desired. If desired the back mat may be protected in knownmanner by a thin sheet metal position and there held and the platen H.is-

adjusted vertically by means of hand wheel l4 to a position where thespacing between the roll 2| and the platen I! is approximately equal tothey thickness of the plate 31. With the parts thus adjusted controllever is then moved into feed ing position and the carriage 4 is causedto move from its extreme right hand position toward the left. In somoving the plate 31, as appears at the right in Fig. 5, is broughtbeneath th roll 2| as appears more clearly in the center portion of Fig.with a resulting downward displacement of the printing face of the plate31 opposite the portions covered by the mat 39 and a reswlting upwarddisplacement of the printing face of the plate 31 in the portionsopposite the mat 3B. In this way the printing face of the plate 31 iscaused to assume, in predetermined local areas, predeterminedalterations in level. This alteration in the level of predeterminedareas of the printing face is availed of subsequently in producingdesired printing effects.

In so acting upon the plate 31 the roll 2i pro duces a deformation ofthe metal contained in the plate. This deformation gives rise to asocalled cold worked condition in the metal which momentarily for a merematter of seconds leaves the plate in a more easily machined condition.The back of the plate 31 after embedment cf the back mat 39 is no longerfiat and in order that the plate be precisely and solidly held in apress it is necessary to return the back surface of the plate 31 to aplane condition. In accordance with this invention the correction of theback surface of the plate 31 is accomplished by shaving the sameimmediately following, within a matter of seconds, the treatment appliedby the roll 2 l.

Shaving of the plate 3 1'is performed by the shaving sub-assembly 2|]previously referred to.

Shaving assembly 25 is made up, as appears more clearly in Fig. 3, of ahorizontally disposed knife supporting beam 4|] rigidly secured to sideframe members I6 and IT. The forward face of beam 45 is inclined asshown to provide a firm backing for an angularly disposed shaving knife4| held firmly in place by a plurality of spaced anchoring bolts 42, oneof which is shown in Fig. 3. Anchoring bolts 42 pass through openings 53in the beam 40 which openings 43 are slightly larger in diameter thanthe bolts 42 thus providing a limited scope for vertical adjustment ofknife 4|.

To provide a means for precisely positioning the knife 4| and to ensureits maintenance in fixed position, a shoulder block 44 is securelyaffixed to the beam 45 above the knife 4|. Extending through theshoulder block 54 in threaded engagement therewith is a plurality ofhorizontally ranged adjusting screws, one of which is shown at 45, thesame being positioned to bear upon the upper edge of the knife 4|.Adjusting screws 45 are each provided with lock nuts 45 for holding thescrews in predetermined position once an adjusted position for the knife4| has been achieved. 7

Knife 4| is preferably adjusted to and held in a position slightlycloser to the platen than the spacing between roll 2| and the platenthis difference in spacing being equivalent to the optimum thickness ofa shaving which may be removed by the knife 4|. If desired roll 2| mayof course also be arranged to approach the platen II more closely thanthe knife 4|, in cases where for any reason it is desired to avoidshaving a plate which is subjectedto treatment by roll 2|. In caseswhere a back mat such as 39 and a metal protecting sheet are employedand it is desired to avoid damage to the same upon approach to the knife4| and mat 39 and protecting sheet may be lifted as indicated in Fig. 5,and drawn upwardly behind roll 2| immediately following application ofpressure by the roll 2|.

As a part of the shaving assembly 2|], and for the purpose of steadyinga plate 31 while being subjected to shaving, a series of spring pressedrollers 41 are arranged beneath the beam 40, so as to bear upon theplate 31 with a steadying pressure insufficient to cause deformation ofthe plate 31.

Where the object to be accomplished is the straightening orsolidification of a printing plate rather than so-called treatment ofthe same, the plate is first approximately dimensioned by roughing andshaving in its unstraightened and unsolidified condition, using thereforapparatus well known in the art. The approximately dimensioned plate isthen placed upon the platen while at the right end appropriateadjustments are made to bring into operation the solidifying andstraightening assembly l9.

The solidifying and straightening assembly I9 derives its support fromside frame members It and i1 and from a stationary box beam 48 extendingbetween said side frame members, rigidly secured thereto by screws 45 asshown. Surrounding box beam 48 and vertically slideable with respectthereto is a transverse roller supporting yoke made up of a top plate5|), screw fastened to a pair of downwardly extending side shell members5| and 52. The inner faces of side shell members 5| and 52 are preciselydimensioned at 53 and 54 respectively to bear with a close sliding fitagainst the sides of the box beam 48, and similarly at 55 and 56 to bearwith a close sliding fit against the side faces of inwardly projectingbosses 51 and 58 formed respectively as integral extensions of sideframe members It and I1. In this way the roller supporting yoke isclosely held against tilting while at the same time limited freevertical movement is permitted.

Securely attached to the side shell members 5| and 52 near their endsand beneath the same is a pair of bearing hangers 59 and 55. Mounted forfree rotation within the bearing hangers 59 and 60 is a dentatedsolidifying roll 6| the surface of which is uniformly covered with apattern of pyramidal projections as shown in greater detail in Fig. 9Also held between the side shell members 5| and 52 by fastening meansnot shown is a bottom plate 52 which serves to render the roller supportyoke a roughly rectangular shell surrounding the box beam 48. Betweenthe top of the box beam 48 and the top plate 58, in recesses providedtherefor are three expansion springs 63 the tension of which issufficient to more than support the entire weight of the rollersupporting yoke and associated parts thus causing this assembly to betranslated upwardly in the absence of downwardly acting force.

The bottom plate 62 is provided with upwardly facing inclined lands 64which are integrally formed as a part thereof. Between the bottom plate62 and the bottom of box beam 48 there is provided a horizontallyslideable wedge member 65 having inclined faces of a pitch correspondingwith that of the inclined lands fi l with the result that when wedgemember 65 is moved toward the left as depicted in Fig. 6 roller GI andits supporting yoke is forced downwardly against the action of thesprings 63.

For the purpose of controlling the lateral position of wedge member 65,a nut 66 received within a slot in the wedge member 55 is arranged tothreadingly engage a screw shaft 61 which in turn is mounted forrotation in a bearing 68 carried in the boss The outer end of shaft 6?carries an adjusting hand wheel 68 arranged exterior to outboard bearing69 and micrometer indicating mechanism 10. In this way rotation of thehand wheel 68 causes vertical adjusting movement to take place in roll6|. By reason of the extensive area of engagement between wedge member65, the yoke assembly on one hand and the bottom of box beam 48 on theother hand, the roller BI is very rigidly held against upwarddisplacement in any position of adjustment.

Between the bearing hangers 5S and 60, side shell members 5! and 52 areextended downwardly to form supports for spring pressed steadying rollsH and 12 which are arranged to bear with a light but steadying pressureagainst a plate 3'1 carried on the platen i i.

In acting upon an approximately dimensioned printing plate 37 with thesolidifying sub-assembly l9, platen II is first vertically adjustedthrough manipulation of hand wheel M to cause the plate 31 to assume aposition in which the same will be subjected to shaving to anappropriate degree b the knife 4|. To facilitate such adjustmentmicrometer indicating means '13 is associated with adjusting screw i3.Having brought about adjustment of the platen ii for the degree ofshaving desired hand wheel 68 is then manipulated to cause the roll 6!to assume a position of predetermined distance below the top level ofplate 31. With this adjustment, platen H is caused to move toward theleft in Fig. 1 and the plate 31 is caused to pass beneath the roll Eland the knife 4: becoming acted upon in a manner diagrammaticallyindicated in Fig. 4.

As indicated, toward the right in Fig. 4 the plate 31 when placed uponthe platen H may be possessed of inaccuracies in the plane of theprinting face as indicated at M as well as areas of deficient density asindicated at 15. The plate 3'! having passed beneath the roll 6| asindicated in the central portion of Fig. 4 is caused by pressure induceddeformation of the metal of the plate to be brought to a condition wherethe printing face of the plate is corrected and the areas of reduceddensity are compacted. In so doing the metal composing the plate 31' andparticularly a layer of the same directl beneath the roll Bl, asindicated by stippling and the numeral I6, is rendered momentarily moreeasily cut and machined. Thereafter the plate 3'! moves with littlelapse of time directly into contact with the knife 4! which acts toremove a very precisely cut surface shaving as indicated at the left inFig. 4. When a plate such as 3! is shaved as explained above immediatelyfollowing pressure deformation and before aging of the cold workedcondition metal sets in to an appreciable degree, the stresses createdin the plate due to the shaving action are much reduced with the resultthat deformation of the plate due to the shaving action is minimized.

This is in contrast to the action which occursv when a plate is shavedwithout taking advantage of the momentary increased machinabilityproduced by cold working under which circumstances the stresses createdin the plate due to the shaving action at times causes lifting of localareas of the type face of the plate with the result that the desiredprecisely positioned relationship of the type face to the back of theplate is not obtained.

From the foregoing it may be observed that the apparatus and method ofthis invention may be employed for the solidification and straighteningof an approximately dimensioned printin plate and for the simultaneousshaving of the same to produce a plate of increased dimensional accuracynot heretofore obtainable with apparatus and methods heretoforeemployed. If desired the apparatus and method of this invention maylikewise be employed for the simultaneously treating and shaving of aplate to bring about a predetermined arrangement of levels of localareas of the type face with relationship to the back of the plate. Itwill be un derstood, however, that a printing plate ordinarily is to beacted upon alternatively by one or the other of the foregoing actions.When a plate is to be subjected to solidification and straightening theroll 5! is lowered and roll 2! is raised to inactive position. On theother hand, if a plate is to be subjected to treatment by roll 2! thelatter is lowered and roll 6! is raised to inactive position. Under someexceptional circumstances conditions may arise where rolls 2| and GI'may both be lowered to active position and the plate 37 may be subjectedsuccessively to the action of both rolls and then immediately shaved.

We claim:

1. The method of acting on a printing plate formed of a metal alloycontaining a predominant proportion of lead for the purpose ofestablishing a predetermined dimensional relationship between theprinting face and the back of the plate which consists in placing theprinting face of the plate in contact with a rigid nondeformablesupporting surface having a predetermined contour coincident with theprinting face contour desired, progressively applying rolling pressureto the back of said plate to be acted upon in amount sufficient to causepermanent deformation of the metal alloy in said plate with displacementof the printing face of said plate into conformity with the contour ofsaid supporting surface, said rolling pressure also being in amountsufficient to establish a coldwork induced temporary increasemachinability of said metal alloy, and then while said printing faceremains in contact with said supporting surface and while said temporaryincreased machinability persists immediately shaving the back of saidplate to a surface having a predetermined dimensional relationship tothe printing face of said plate.

2. The method of acting upon a printing plate in accordance with claim 1wherein the nondeformable supporting surface is a plane surface andwherein the rolling pressure is applied in a pattern of closely spaceddiscontinuous areas whereby the printing plate is straightened andsolidified.

3. The method of acting upon a printing plate in accordance with claim 1wherein the nondeformable supporting surface is provided with .DONALD C.COTTRELL.

CARL C. SWEET.

References Cited in the, file of this patent UNITED STATES PATENTSNumber Name Date McKee Apr. 4, 1911 Number 10 Name Date Droitcour Oct.10, 1911 McKee Nov, 4, 1913 Erickson Feb. 17, 1925 Claybourn Aug. 11,1925 Claybourn Nov. 16, 1926 Erickson Feb. 8, 1927 Claybourn Mar. 27,1928

